Hitherto, increase in the quantity of heat generated from a heater such as an IC (integrated circuit) due to a higher performance of a PC (personal computer) causes a problem, and a variety of heat dissipation methods are proposed or commercialized. With one of the methods for dissipating the heat, by arranging a heat dissipation fin composed of metal such as aluminum to contact with the IC, heat is conducted from the IC to the fin so as to be dissipated. Also, with another one of the methods, by employing a fan, hot air in a housing of, e.g., a PC is forcefully repelled, low-temperature circumambient air is introduced to the surrounding of the heater so as to achieve heat dissipation. With another one of the methods, by employing a dissipation fin and a fan together, hot air around the dissipation fin is forcefully rejected with the fan while making the contact area between a heater and air wider.
Unfortunately, forceful circulation by such a fan generates a temperature boundary layer on the surface of a downstream part of the dissipation fin causes a problem that heat cannot be effectively released from the dissipation fin. In order to solve such a problem, although increasing the wind speed of the fan so as to make the temperature boundary layer thinner can be a candidate, increasing the number of revolution of the fan in order to increase the wind speed causes a problem that a noise is generated by the bearing section of the fan or a wind noise is generated due to a wind from the fan.
In some methods for breaking the temperature boundary layer so as to effectively release heat, a synthetic jet flow is utilized. This is intended to eject moving air generated, e.g., by a reciprocating piston provided in a chamber, though a hole perforated at one end of the chamber. The air ejected through the hole is called a synthetic jet flow and facilitates mixture of air so as to break the temperature boundary layer, thereby more effectively dissipating heat than by known forceful circulation with a fan (see, e.g., Description of U.S. Pat. No. 6,123,145 (FIG. 8, and so forth) and Japanese Unexamined Patent Application Publication 2000-223871 (FIG. 2)).
Unfortunately, with the technique set forth in Description of the foregoing U.S. Pat. No. 6,123,145, vibration of air due to a reciprocal motion of the piston propagates as a sound wave, thereby causing the sound wave to occur a noise problem. Also, since the trend of an IC for a higher clock in recent years causes the quantity of generated heat to grow steadily, in order to break the temperature layer formed in the vicinity of the dissipation fin, due to the heat generation, sending a more quantity of air towards the IC and the dissipation fin than ever is needed. If done so, even in an apparatus of ejecting air by vibrating a timbale as that shown in FIG. 1A disclosed in Description of the foregoing U.S. Pat. No. 6,123,145, the ejection quantity of air must be increased by making the amplitude of the vibration greater. Accordingly, if the frequency of the timbale is in an audible band, a problem of a noise of the timbale also occurs. On the contrary, while a decrease in the frequency reduces a noise, the ejection quantity of air decreases accordingly.
In view of the above-described circumstances, an object of the present invention is to offer a gas ejector capable of effectively dissipating heat generated from a heater while inhibiting noise generation as little as possible, an electronic device equipped with the gas ejector, and a gas-ejecting method.